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Ex 5.1, 1 Prove that the function 𝑓 (π‘₯) = 5π‘₯ – 3 is continuous at π‘₯ = 0, at π‘₯ = –3 and at π‘₯ = 5 Given 𝑓(π‘₯)= 5π‘₯ –3 At 𝒙=𝟎 f(x) is continuous at x = 0 if (π₯𝐒𝐦)┬(π±β†’πŸŽ) 𝒇(𝒙) = 𝒇(𝟎) (π₯𝐒𝐦)┬(π±β†’πŸŽ) 𝒇(𝒙) "= " lim┬(xβ†’0) " "(5π‘₯βˆ’3) Putting x = 0 = 5(0) βˆ’ 3 = βˆ’3 𝒇(𝟎) = 5(0) βˆ’ 3 = 0 βˆ’ 3 = βˆ’3 Since L.H.S = R.H.S Hence, f is continuous at 𝒙 = 𝟎 At x = βˆ’3 f(x) is continuous at x = βˆ’3 if ( lim)┬(xβ†’βˆ’3) 𝑓(π‘₯)= 𝑓(βˆ’3) Since, L.H.S = R.H.S Hence, f is continuous at 𝒙 =βˆ’3 (π₯𝐒𝐦)┬(π±β†’πŸ‘) 𝒇(𝒙) "= " lim┬(xβ†’3) " "(5π‘₯βˆ’3) Putting x = βˆ’3 = 5(βˆ’3) βˆ’ 3 = βˆ’18 𝒇(βˆ’πŸ‘) = 5(βˆ’3) βˆ’ 3 = βˆ’15 βˆ’ 3 = βˆ’18 At 𝒙 =πŸ“ f(x) is continuous at x = 5 if ( lim)┬(xβ†’5) 𝑓(π‘₯)= 𝑓(5) Since, L.H.S = R.H.S Hence, f is continuous at x = 5 Thus, the function is continuous at x = 0, x = βˆ’3, x = 5 (π’π’Šπ’Ž)┬(π’™β†’πŸ“) 𝒇(𝒙) "= " (π‘™π‘–π‘š)┬(π‘₯β†’5) " "(5π‘₯βˆ’3) Putting x = 5 = 5(5) βˆ’ 3 = 22 𝒇(πŸ“) = 5(5) βˆ’ 3 = 25 βˆ’ 3 = 22

  1. Chapter 5 Class 12 Continuity and Differentiability
  2. Serial order wise

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 15 years. He provides courses for Maths, Science and Computer Science at Teachoo